Opponents of a new law that requires schools to teach about the contributions of gay, lesbian, bisexual and transgender people as well as people with disabilities have only one more day to get enough voter signatures to attempt to repeal the measure.

The group, Stop SB48, needs more than half a million signatures to put a referendum before voters next year. The nearly all-volunteer effort has been sending out increasingly desperate calls for help in fighting the controversial law, which requires LGBT history to be included in textbooks and classroom instruction.

Late last week the group sent an e-mail to supporters that said flatly, "We do not have enough signatures."

However, supporters of SB48 are not claiming victory. The spokeswoman for Equality California, the state's major LGBT rights organization, said the real push to overturn the law could come in the form of a second ballot initiative aimed at the November 2012 election.

"We always imagined they would try to take another bite at the apple in November," said Rebekah Orr, a group spokeswoman. "If they don't qualify in a few days, then we need to be prepared for them to qualify in November."

If they chose to go that route, opponents of the law could change their proposed initiative to address only the teaching of LGBT contributions and not the less-controversial provision that mandates inclusion of people with disabilities.

Karen England, the executive director of the Capitol Resource Institute and leader of the Stop SB48 campaign, said she was confident they would collect enough signatures to qualify the referendum this week.

504,760 names needed

They need to collect the signatures of 504,760 registered voters by Wednesday to qualify the referendum.

Asked about the prospect of a November 2012 ballot measure, England said gay rights groups "should be concerned that families and taxpayers in the state aren't going to stand for" textbooks that include transgender people, among others.

A successful ballot initiative would probably have to be a constitutional amendment instead of a simple change to state law. That's because LGBT people were given the highest level of minority protection from laws targeting them under a ruling by the state Supreme Court during proceedings regarding same-sex marriage.

Under the law, beginning on Jan. 1 schools in California must include the contributions of LGBT people and people with disabilities in social science instruction. Textbooks also must include those contributions, though the state's budget crisis has delayed purchasing of new textbooks until at least 2015.

The state already mandates inclusion of minority groups, including African Americans, Asian Americans and American Indians, among others.

Other states use the textbooks approved by California because publishers often tailor the texts to standards here because of the sheer number of books purchased by the state, meaning the law could reverberate nationwide.

Some legislators argued that it would help to combat bullying of LGBT students, which has led to a rash of U.S. suicides, by showing them examples of accomplished gay and lesbian historical figures. Opponents called it a distraction to what students should be learning in schools and also cited religious objections to homosexuality.

Concerns about schools teaching about homosexuality have been a central plank in anti-gay-rights efforts for decades, including in the campaign to ban same-sex marriage. Some of the deep pockets that supported Proposition 8 would not say whether they support a referendum on the teaching issue in November 2012.

Groups don't donate

Gay rights supporters have been surprised that national conservative organizations have not donated large sums to the referendum effort, adding to the speculation about a November ballot initiative.

Colorado's Focus on the Family gave more than $630,000 to pass Prop. 8. Asked about the prospect of a November 2012 campaign, spokeswoman Monica Schliecher said in a statement, "Thanks for your inquiry ... about our possible efforts to repeal the LGBT textbook law. We'll be declining this opportunity to speak, however."

Sen. Mark Leno, D-San Francisco, who introduced SB48, said that he thinks such an initiative could actually be easier to defeat on a November ballot.

He said he will not be surprised if an initiative campaign starts, but said that would give gay rights proponents an opportunity to talk to voters about "a mean-spirited, extreme minority which does not want civil rights history to be taught and wishes that entire chapter of history would be ignored and just go away."